A Tree Is Alive

art by Jo Lynn Alcorn

It may not look like it, but a tree is alive. It breathes and drinks and eats, like other living things. And it grows, too—very slowly.

A tree begins as a seed. Some seeds are protected inside nuts or fruits or pine cones. Maple seeds have thin, wing-shaped coverings. They whirl and twirl and spin as they are carried by the wind. Some land on hard, rocky places or in lakes or rivers. Some are eaten by birds, squirrels, and other animals. But some land on soft, rich soil, where they can grow.

Warmed by the sun and watered by spring rains, the seed pushes out a thin, white root.

A small stem grows up from the ground. It will be the tree's trunk.

Two small leaves, called seed leaves, open. More roots grow from the first root.

Maple leaves appear, and the plant grows bigger and bigger.

A Sugar Maple Tree

Leaves make food for the tree. Branches stretch out from the trunk to let sunlight reach the leaves.
Using the energy from sunlight, green leaves combine carbon dioxide with water from the roots to make a nourishing sugary sap.Back to Top

A leaf “breathes” through many thousands of tiny holes on its surface. It takes in a gas called carbon dioxide from the air and gives off oxygen.
When you breathe, you take in the oxygen given off by trees and other plants, and breathe out carbon dioxide.Back to Top

When fall comes and daytimes get shorter, a little corky layer grows where each leaf stem joins a tree branch. This blocks the flow of water to the leaf.
Without water, the leaf dies. It loses its green color and shows yellows and orangy reds that had been hidden by the green. When the dead leaves fall, the tree is ready for winter, a time when sunlight and water are scarce.Back to Top

Just as blood flows through your body, sap flows through a tree. Inside the tree trunk and branches, tiny tubes carry water and minerals up from the roots to the leaves.
More tubes carry the sugary food made by the leaves to all the other parts of the tree. Veins in each leaf are like tiny pipes carrying food and water.Back to Top

Bark is the skin of the tree. It protects the inside of the tree from animals and bad weather. Some trees have bark that stretches easily as they grow, so the bark stays smooth.
But most trees have bark that cracks and gets rough as the tree grows fatter.Back to Top

Roots are the feet of the tree—only they're underground. They help keep the tree from falling down. The bigger the tree, the longer its roots have to be.
The roots also help feed the tree, soaking up water and minerals from the soil.Back to Top

Pine trees don't need to lose their tough, thin leaves, called needles, for winter. The needles have a waxy coating that protects them from cold, dry winter weather.

Vocabulary

cone:

The part of a pine tree where seeds grow.

roots:

The parts of plants that take in water from the ground.

seed:

The part of a plant that has a new plant inside it.

trunk:

The thick middle part of a tree. The trunk of a tree grows up from the ground.